Trevejo RT, Lefebvre SL, Yang M, Rhoads C, Goldstein G, et al. Survival analysis to evaluate associations between periodontal disease and the risk of development of chronic azotemic kidney disease in cats evaluated at primary care veterinary hospitals. J Am Vet Med Assoc. 2018 Mar 15;252(6):710-720.
Chronic kidney disease is a common and often fatal disease of cats. Many factors have been proposed as possible causes of CKD. It is likely that the development of this condition is likely a combination of genetic, degenerative, infectious, toxic, environmental, and other contributing factors. Previous studies in dogs, cats, and humans have identified periodontal disease (PD) as a factor associated with CKD in cats. It has been theorized that periodontal disease may contribute to a subclinical inflammatory state leading to renal hypoxia and the development of CKD. Conversely, CKD may lead to uremic damage to the gums, exacerbating PD.
The purpose of this study was the determine if cats with PD were at increased risk of developing CKD, and to further determine if the risk of CKD was correlated with the grade of PD. The study was designed as a retrospective cohort study of all cats evaluated >3 times in an 11 year period at a group of 829 veterinary hospitals. Cats were required to have full signalment recorded and were excluded if they gave CKD or AKI has a health reason at the time of enrollment to the study.
Cats were evaluated for periodontal disease and included in the “exposed” cohort if they had a recorded stage of PD. Non exposed cohort had no recorded PD, gingivitis, periodontal pockets, or gingival recession. Exposed cats were mated with non-exposed in a 1:2 ratio by year of presentation and age. PD was staged as stage 1 to 4 based on physical exam findings with or without dental radiographs.
2,383,820 cats were screened, of which 56,414 cats were enrolled with PD (~7%). These were matched with control cats for a total population size of 169,242 cats in the study. 3022 cats (1.8%) developed CKD over the course of the study. In univariate analysis, cats with CKD were more likely to have PD stage 2 or greater. They were also more likely to be older, female, neutered and purebred, and had more dental cleanings, recent anesthesia, and FVRCP vaccinations. Cats with PD were more likely to have cardiomyopathy, cystitis, diabetes, FIV, hypertension, hyperthyroidism, stomatitis, dental resorptive lesions, and toxoplasmosis.
In multivariate analysis, risk of CKD was found to be significantly higher in cats with any stage of PD than in control cats. For cats with stage 3-4 PD, risks of CDK were 1.5x that of cats without PD. Differences in risk between categories were not statistically significant.
Risk of CKD also increased with age, with a 40% increase in risk per year. Purebred cats had increased risk compared to mixed breeds, and cats with recent general anesthesia were at increased risk. Cats with cystitis had increased risks of CKD, and this was more significant in females than males. Cats with diabetes mellitus and hepatic lipidosis had a lower risk of disease than cats without.
The authors conclude that breed, age, and severity of periodontal disease are major risk factors for the development of CKD in domestic cats. Purebreds are likely at increased risk compared to mixed breed cats, likely due to genetic influences. Some treatment factors, such as anesthesia, may also have contributed to the risk of CKD developing,
The use of a retrospective methodology is a potential flaw in the study especially since it relied on medical records rather than direct examination of patients. The study did not investigate factors such as muscle wasting and proteinuria that may affect staging of CKD. Diagnosis of PD by multiple observers and without consistent radiography may limit detecting and alter staging of disease.
Overall, this was a large study that examined a significant number of cats with both PD and CKD, and suggests some factor(s) that may be associated with development of kidney disease. The presence of PD prior to diagnosis of CKD gives some suggestion that the relationship may be causational rather than simply correlational, though further work is needed to confirm this. (MRK)